def _minimax(self, board: chess.Board, alpha: float, beta: float,
depth: int):
if depth == 0 and any(board.legal_moves):
return self._evaluate_board(board), None
# Draw
elif (board.can_claim_draw() or board.is_stalemate()
or board.is_insufficient_material()):
return 0, None
# White wins
elif board.is_checkmate() and board.turn == chess.BLACK:
return float('inf'), None
# Black wins
elif board.is_checkmate() and board.turn == chess.WHITE:
return float('-inf'), None
best_eval, best_move = float('-inf'), None
for move in board.legal_moves:
board.push_uci(str(move))
cur_eval, cur_move = self._minimax(board, -beta, -alpha, depth - 1)
cur_eval = -cur_eval
board.pop()
if best_eval < cur_eval:
best_eval = cur_eval
alpha = cur_eval
best_move = move
if best_eval >= beta:
break
return best_eval, best_move
def minimax_root(depth: int, board: chess.Board) -> chess.Move:
# White always wants to maximize (and black to minimize)
# the board score according to evaluate_board()
maximize = board.turn == chess.WHITE
best_move = -float("inf")
if not maximize:
best_move = float("inf")
moves = get_ordered_moves(board)
best_move_found = moves[0]
for move in moves:
board.push(move)
# Checking if draw can be claimed at this level, because the threefold repetition check
# can be expensive. This should help the bot avoid a draw if it's not favorable
# https://python-chess.readthedocs.io/en/latest/core.html#chess.Board.can_claim_draw
if board.can_claim_draw():
value = 0.0
else:
value = minimax(depth - 1, board, -float("inf"), float("inf"), not maximize)
board.pop()
if maximize and value >= best_move:
best_move = value
best_move_found = move
elif not maximize and value <= best_move:
best_move = value
best_move_found = move
return best_move_found
def self_play(b: Board):
while not b.is_game_over():
if b.can_claim_draw():
print("Draw")
break
m = pick_move(b)
print(f"\nMaking move {m}")
b.push(m)
print(b)
result = b.result()
print(f"\n\nGame Over: {result}")
return result, b
def dfs(state, num_searches, isplayer):
comp = max if isplayer else min
board = Board(state)
if (board.is_checkmate()):
return 0.0 if isplayer else 1.0
if (board.is_stalemate()):
return 0.5
if (board.can_claim_draw()):
return 0.5
rv = 0.0 if isplayer else 1.0
moves = list(board.legal_moves)
# if number of nodes to search exceeds the search limit provided
# score all nodes
if (len(moves) > num_searches):
for move in moves:
board.push(move)
rv = comp(rv, score(board.fen()))
board.pop()
return rv
search_move = [False for _ in range(len(moves))]
search_count = 0
i = 0
while i < len(moves):
inc = min(60, len(moves) - i)
# gives 50% chance for all nodes to be searched
# TODO make an adjustable probability parameter
tp = random.randrange(1 << inc)
while tp > 0:
if (tp & 1):
search_move[i] = True
search_count += 1
tp >>= 1
i += inc
score_count = len(moves) - search_count
nodes_per_search = 0
if (search_count != 0):
nodes_per_search = (num_searches - score_count) // search_count
vals = []
for i in range(len(moves)):
move = moves[i]
if search_move[i]:
board.push(move)
rv = comp(rv, dfs(board.fen(), nodes_per_search, not isplayer))
board.pop()
else:
board.push(move)
rv = comp(rv, score(move))
board.pop()
return rv
def score_material_and_win(b: Board) -> int:
if b.can_claim_draw():
return 0
if b.is_game_over():
res = b.result()
if res == '1/2-1/2':
return 0
elif res == '1-0':
return 9999
elif res == '0-1':
return -9999
else:
raise RuntimeException(f"Unknown result {res}")
else:
return score_material(b)
def write_json(self, board: chess.Board):
"""
Writes all of the board info in json
"""
best_move = self.get_best_move(board)
output = OrderedDict([
('fen', board.fen()),
('fullmoveNumber', board.fullmove_number),
('result', board.result()),
('isGameOver', board.is_game_over()),
('isCheckmate', board.is_checkmate()),
('isStalemate', board.is_stalemate()),
('isInsufficientMaterial', board.is_insufficient_material()),
('isSeventyfiveMoves', board.is_seventyfive_moves()),
('isFivefoldRepetition', board.is_fivefold_repetition()),
('white',
OrderedDict([
('hasKingsideCastlingRights',
board.has_kingside_castling_rights(chess.WHITE)),
('hasQueensideCastlingRights',
board.has_queenside_castling_rights(chess.WHITE)),
])),
('black',
OrderedDict([
('hasKingsideCastlingRights',
board.has_kingside_castling_rights(chess.BLACK)),
('hasQueensideCastlingRights',
board.has_queenside_castling_rights(chess.BLACK)),
])),
('turn',
OrderedDict([
('color', 'white' if board.turn is chess.WHITE else 'black'),
('isInCheck', board.is_check()),
('bestMove', best_move),
('legalMoves', [move.uci() for move in board.legal_moves]),
('canClaimDraw', board.can_claim_draw()),
('canClaimFiftyMoves', board.can_claim_fifty_moves()),
('canClaimThreefoldRepetition',
board.can_claim_threefold_repetition()),
])),
])
self.finish(output)
def move(self, board: chess.Board) -> chess.Move:
value = -float('inf') if self.player_color else float('inf')
best_move = None
legal_moves = list(board.legal_moves)
for move in legal_moves:
board.push(move)
if board.is_checkmate():
board.pop()
return move
if board.can_claim_draw():
temp = 0
else:
temp = minimizer(
board, self.max_depth,
self.evaluate) if self.player_color else maximizer(
board, self.max_depth, self.evaluate)
if board.is_game_over():
value = max(
value, self.evaluate(board)) if self.player_color else min(
value, self.evaluate(board))
if self.player_color:
if temp >= value:
value = temp
best_move = move
else:
if temp <= value:
value = temp
best_move = move
board.pop()
continue
if self.player_color:
if temp >= value:
value = temp
best_move = move
else:
if temp <= value:
value = temp
best_move = move
board.pop()
self.move_count += 1
return best_move
def featureEngineering(id, game, game_collection):
counter = 0
update_dict = {}
first_check = True
first_queen_move = True
features_dict = defaultdict(int)
# {
# 'promotion': 0,
# 'total_checks': 0,
# 'is_checkmate': 0,
# 'is_stalemate': 0,
# 'insufficient_material': 0,
# 'can_claim_draw': 0
# }
board = None
for moveDBObject in game['moves']:
# print(f"\tUpdating {move['uci']} -> {move['turn']}")
board = Board(moveDBObject['fen'])
uci = moveDBObject['uci']
move = Move.from_uci(uci)
moved_piece = board.piece_at(move.from_square)
captured_piece = board.piece_at(move.to_square)
if moved_piece == QUEEN and first_queen_move:
features_dict['queen_moved_at'] = board.fullmove_number
first_queen_move = False
if captured_piece == QUEEN:
features_dict['queen_changed_at'] = board.fullmove_number
if move.promotion:
features_dict['promotion'] += 1
if board.is_check():
features_dict['total_checks'] += 1
if first_check:
features_dict['first_check_at'] = board.fullmove_number
first_check = False
# castling
if uci == 'e1g1':
features_dict['white_king_castle'] = board.fullmove_number
elif uci == 'e1c1':
features_dict['white_queen_castle'] = board.fullmove_number
elif uci == 'e8g8':
features_dict['black_king_castle'] = board.fullmove_number
elif uci == 'e8c8':
features_dict['black_queen_castle'] = board.fullmove_number
# update_dict[f"moves.{counter}.turn"] = counter % 2 == 0
counter += 1
if counter > 0:
if board.is_checkmate():
features_dict['is_checkmate'] += 1
if board.is_stalemate():
features_dict['is_stalemate'] += 1
if board.is_insufficient_material():
features_dict['insufficient_material'] += 1
if board.can_claim_draw():
features_dict['can_claim_draw'] += 1
features_dict['total_moves'] = board.fullmove_number
piece_placement = board.fen().split()[0]
end_pieces = Counter(x for x in piece_placement if x.isalpha())
# count number of piece at end position
features_dict.update(
{'end_' + piece: cnt
for piece, cnt in end_pieces.items()})
# print(features_dict)
game_collection.update_one({"_id": ObjectId(id)},
{"$set": features_dict},
upsert=False)
